Cosmic Rays and Muon Production
High-energy protons and heavy nuclei originating from deep space collide with the upper layers of the Earth's atmosphere (~15 km altitude).
These interactions produce unstable particles known as pions and kaons. These particles rapidly decay into muons and neutrinos.
A muon is a fundamental particle similar to the electron but approximately 207 times heavier. Due to relativistic time dilation, muons can reach the Earth's surface despite their short lifetime (~2.2 µs).
Muon Interaction with Matter
As muons pass through matter, they produce two primary physical effects:
- Energy loss (ionization): The muon deposits energy while traversing matter. Dense and high-mass materials absorb more energy.
- Coulomb scattering: The electric field of atomic nuclei slightly deflects the muon trajectory. The scattering magnitude is proportional to Z² — meaning heavier nuclei produce stronger scattering effects.
Why Can Muons Penetrate So Deep?
Unlike conventional X-rays and gamma rays, muons possess extremely high energies. At sea level, a muon with an average energy of ~4 GeV can penetrate
tens of meters of concrete or rock. This characteristic fundamentally distinguishes muon tomography from other non-destructive inspection techniques.
| Muon Energy |
Range in Concrete |
Range in Rock |
Application |
| 100 MeV |
~30 cm |
~20 cm |
Shallow structure analysis |
| 500 MeV |
~2.5 m |
~1.5 m |
Internal building imaging |
| 1 GeV |
~8 m |
~5 m |
Shallow geological analysis |
| 4 GeV (average) |
~40 m |
~25 m |
Mineral exploration |
| 10 GeV |
~120 m |
~80 m |
Deep geological analysis |
| Muon penetration range in matter according to energy level (25°C, density: concrete 2.3 g/cm³, rock 2.7 g/cm³) |
Detector System
Basic Operating Principle
The system consists of two vertically stacked detection panels. Each panel records the position and timing information of traversing muons.
Simultaneous triggering of both panels (coincidence detection) indicates a genuine muon event; this method significantly suppresses electronic noise and background radiation.
Detection Layers
Each detection panel consists of two primary components:
- Scintillator material: Produces photons (light) during muon passage. Plastic scintillators convert the deposited muon energy into visible light.
- Photodiode array: Converts photons emitted by the scintillator into electrical signals. Each array element records light originating from different regions, enabling high-precision localization of the interaction point.
Position Reconstruction
For each detected muon, the system records the impact coordinates on the upper panel (x₁, y₁), the impact coordinates on the lower panel (x₂, y₂), and the trigger timing of both panels.
Using these data, the muon incidence angle is calculated and the probable scattering point along the trajectory is reconstructed using ray-tracing techniques.
The PoCA (Point of Closest Approach) algorithm compares incoming and outgoing muon tracks to estimate the scattering location and scattering magnitude.
High scattering values indicate the presence of high-Z materials.
Detectable Minerals and Elements
The following table presents the principal minerals and metals detectable by muon tomography, together with their detection performance and minimum acquisition times.
The specified durations are based on the minimum statistical conditions required for our current dual-panel system configuration operating at a measurement distance of 1 meter.
| Mineral / Element |
Symbol |
Z |
Detection Capability |
Min. Duration |
Application |
| Gold |
Au |
79 |
Excellent ★★★★★ |
2 hours |
Mineral exploration, security |
| Platinum |
Pt |
78 |
Excellent ★★★★★ |
2 hours |
Precious metal detection |
| Lead |
Pb |
82 |
Excellent ★★★★★ |
1 hour |
Radiation shielding, structural analysis |
| Tungsten |
W |
74 |
Very Good ★★★★☆ |
2 hours |
Rare mineral exploration |
| Bismuth |
Bi |
83 |
Excellent ★★★★★ |
2 hours |
Industrial applications |
| Uranium |
U |
92 |
Excellent ★★★★★ |
1 hour |
Nuclear security |
| Thorium |
Th |
90 |
Excellent ★★★★★ |
1 hour |
Radioactive material detection |
| Mercury |
Hg |
80 |
Excellent ★★★★★ |
2 hours |
Industrial detection |
| Silver |
Ag |
47 |
Good ★★★☆☆ |
4 hours |
Precious metals |
| Tin |
Sn |
50 |
Good ★★★☆☆ |
4 hours |
Ore exploration |
| Antimony |
Sb |
51 |
Good ★★★☆☆ |
4 hours |
Mineral exploration |
| Barium |
Ba |
56 |
Good ★★★☆☆ |
4 hours |
Mineral detection |
| Cesium |
Cs |
55 |
Good ★★★☆☆ |
4 hours |
Nuclear applications |
| Gadolinium |
Gd |
64 |
Good ★★★☆☆ |
3 hours |
Rare earth applications |
| Neodymium |
Nd |
60 |
Good ★★★☆☆ |
4 hours |
Rare earths, magnets |
| Dysprosium |
Dy |
66 |
Good ★★★★☆ |
3 hours |
Rare earth applications |
| Lutetium |
Lu |
71 |
Good ★★★★☆ |
3 hours |
Rare earth applications |
| Ytterbium |
Yb |
70 |
Good ★★★★☆ |
3 hours |
Rare earth applications |
| Copper |
Cu |
29 |
Moderate ★★☆☆☆ |
8 hours |
Mining, cable systems |
| Zinc |
Zn |
30 |
Moderate ★★☆☆☆ |
8 hours |
Ore exploration |
| Nickel |
Ni |
28 |
Moderate ★★☆☆☆ |
8 hours |
Mineral exploration |
| Cobalt |
Co |
27 |
Moderate ★★☆☆☆ |
10 hours |
Rare mineral applications |
| Iron |
Fe |
26 |
Moderate ★★☆☆☆ |
8 hours |
Structural analysis |
| Molybdenum |
Mo |
42 |
Moderate ★★★☆☆ |
6 hours |
Ore detection |
| Manganese |
Mn |
25 |
Weak ★☆☆☆☆ |
24+ hours |
Limited applicability |
| Chromium |
Cr |
24 |
Weak ★☆☆☆☆ |
24+ hours |
Limited applicability |
| Titanium |
Ti |
22 |
Weak ★☆☆☆☆ |
24+ hours |
Very weak signal |
| Vanadium |
V |
23 |
Weak ★☆☆☆☆ |
24+ hours |
Very weak signal |
Detection times can be significantly reduced by increasing the number of detector panels and utilizing artificial intelligence-based image enhancement algorithms.
With a 16-panel array configuration, the specified acquisition times can be reduced by approximately 8–10 times.
AI integration can provide an additional 5–20× improvement in reconstruction performance.
Undetectable Materials
(Z < 15, low-density materials)
Organic Materials: Wood, paper, cardboard, textiles; organic fuels (coal, petroleum derivatives).
Polymers / Plastics: Polyethylene (PE), Polypropylene (PP), PVC; composite materials.
Other: Water and liquid substances; biological tissues; glass and ceramics (very weak signal); aluminum (borderline, weak signal).
Conclusion
Muon tomography is a completely non-destructive imaging technology that utilizes natural and cost-free radiation generated by cosmic-origin particles.
Its capability to image high atomic number elements (Z > 25) with high contrast makes this technology highly suitable for valuable mineral exploration,
structural analysis, and security applications.
The system developed by Bilgibiz Ltd. meets the industry's speed and precision requirements through its compact design, real-time data processing capability,
and artificial intelligence integration.
Utilizing well-established physical principles for the detection of gold, tungsten, rare earth elements, and other strategic metals,
this system will contribute significantly to the more efficient evaluation of Türkiye’s underground resource potential.